I come from a fishing community and so rope is freely available. I usually have two strands of electric wire and 3 or 5 strands of rope. My posts are iron re-bar used in construction, covered with White PVC tubing used in plumbing that I bought really cheap at the recycling center.

It works for me but I admit that there are some horses that it won't work with. My Canadian is really smart and she can get out, I'm sure, but she has a serious case of separation anxiety disorder (she was alone most of her 9 years) and so she won't try to leave. My Hanoverian is a big woooose and is scared of the electric wire, even to step over a downed fence.